This invention relates generally to a sheet path baffle for an electrophotographic printing machine, and more particularly concerns a self adjusting sheet guide and a jam removal baffle for a sheet path.
In a typical electrophotographic printing process, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are heated to permanently affix the powder image to the copy sheet.
In printing machines such as those described above, during the fusing process, toner images are fixed to papers by a heated roll that removes moisture from the paper and, as a result, causes the paper to curl due to moisture and temperature gradients across the thickness of the paper. Many copier machines are equipped with decurlers for reducing curl for improving the reliability of paper handling as well as for customer satisfaction.
The curl direction of an incoming sheet to a decurler depends on the curl direction created by a fuser under the effect of image area coverage, paper basis weight and the humidity. It also depends on the system control of a copier machine that may change the orientation of an incoming sheet into the decurler due to the requirement of an output device. For example, in some machines, the input simplex sheets for a mailbox are image down (up curl) while that for a disc finisher are image up (down curl) as a result of inversion of output sheets by an inverter prior to exiting IOT and before entering the disc finisher. Therefore, the entrance baffle assembly of a decurler positioned at the exit of an IOT needs to guide both TI and AI curls as any of above-mentioned output devices can be interchangeably connected to the IOT.
For the ease of clearing a jammed sheet at the decurler entrance, which can occur very frequently because of severely curled sheets entering the decurler, the input device (a fuser or an inverter) which delivers sheets to the decurler is designed to be a slideable module which can be pulled out by an operator for jam clearance or for service. To have sufficient clearance between the two device, a physical gap between the two needs to be designed into a machine for robustness to avoid any possibility of interference due to manufacturing tolerances of the two devices and their supporting frame. This interface gap, however, is a cause for jams of curled sheets if it cannot be closed or reduced during the machine operation to prevent sheets from entering the gap.
It is desirable to have a self-adjusting entrance baffle that is pivotally mounted to the two side plates of the decurler. The entrance baffle has a lower guide surface and an upper guide surface which form a convergent channel for nudging papers into the decurling nip. It is further desirable to have a baffle which will cause jammed sheets to be driven out of a nip for easy jam clearance.
The following disclosures may relate to various aspects of the present invention.